1. Field of the Invention
The present invention relates to a liquid crystal display device for color displaying. For example, the present invention relates to the liquid crystal display device for the color displaying with a liquid crystal panel having color filters of a vertical-stripe type, a mosaic type or a like built therein, and capable of adjusting white balance of a display screen thereof.
The present application claims priority of Japanese Patent Application No.2000-160804 filed on May 30, 2000, which is hereby incorporated by reference.
2. Description of the Related Art
As shown in FIG. 18, a conventional liquid crystal display device includes: a liquid crystal panel 1, a signal electrode drive circuit 2, a scanning electrode drive circuit 3, and a control circuit 4. The liquid crystal panel 1 includes color filters where a pixel is divided into sub-pixels of three primary colors of RGB (Red, Green, Blue). The liquid crystal panel 1 also includes: a plurality of data signal lines X1, . . . , Xn for receiving a sub-pixel data signal D2 corresponding to the sub-pixels of RGB, a plurality of scanning signal lines Y1, . . . , Ym for receiving a scanning signal V3, and a plurality of sub-pixel regions provided at points where each of the data signal lines X1, . . . , Xn and each of the scanning signal lines Y1, . . . , Ym intersect. The sub-pixel data signal D2 is supplied to sub-pixel regions selected from the plurality of sub-pixel regions by a scanning signal V3, and thus a color image corresponding to the sub-pixel data signal D2 is displayed.
The signal electrode drive circuit 2 receives a clock signal ck, a control signal Ct, an image signal V4 for each of RGB, and a central voltage Vs1, generates the sub-pixel data signal D2 by selecting a gradation voltage corresponding to a gradation value of the image signal V4 for each of RGB, and sends the sub-pixel data signal D2 to each of the data signal lines X1, . . . , Xn of the liquid crystal panel 1. The scanning electrode drive circuit 3 sends the scanning signal V3 to each of the scanning signal lines Y1, . . . , Ym of the liquid crystal panel 1 synchronously with the clock signal ck. The control circuit 4 outputs the clock signal ck, the control signal Ct, the image signal V4, and the central voltage Vs1.
FIGS. 19(a), 19(b), and 19(c) are exemplary views showing the above-mentioned color filters used in the liquid crystal panel 1.
The color filter of a vertical-stripe type shown in FIG. 19(a) is suitable for displaying characters, drawings, and the like. The color filters of a mosaic type and a triangle type shown in FIG. 19(b), and 19(c) are ones where the three primary colors of RGB are arranged in a delta state such as stacked-up bricks, which are suitable for displaying moving images such as television (that is, picture data displaying). There is also a horizontal-stripe type color filter. In the horizontal-stripe type color filter, a horizontal line is constituted of pixels of one of the RGB colors, and a line in the vertical direction is constituted of pixels of the three primary colors of RGB.
Adjustment of white balance of a display screen is generally performed by limiting a range of a gradation value of an image signal for each of RGB to be used. For example, in the case where the gradation value of each of RGB is represented by 8-bit data, the gradation value could take values in a range of from 0 to 256. In adjusting the white balance, however, top and bottom of the gradation value of a particular color are cut. For example, regarding the gradation value for R, 0 to 4 and 251 to 255 are cut, and thus the gradation value of 5 to 25 is used. In addition, regarding the gradation value for G and the gradation value for B, 0 to 255 is used.
In adjusting the white balance, as a method of adjusting the gradation voltage for each of RGB without adjustment of the gradation value for each of RGB, there exists a method described in Japanese Patent Laid-open No. Hei4-60583 gazette (hereinafter, referred to as a literature), for example.
FIG. 20 is a circuit diagram showing an electrical configuration of the signal electrode drive circuit 2 described in the foregoing literature.
The signal electrode drive circuit 2 includes: a serial/parallel conversion circuit 2a, decoders 2b1, . . . , 2bn, a color selection circuit 2c, and selection circuits 2d1, . . . , 2dn. The serial/parallel conversion circuit 2a receives the clock signal ck, the control signal Ct and the image signal V4, and outputs gradation values V2a1, . . . , V2an for each of RGB of the image signal V4. The decoders 2b1, . . . , 2bn decode the gradation values V2a1, . . . , V2an, and output selection signals S2b1, . . . , S2bn corresponding to the gradation values V2a1, . . . , V2an. The color selection circuit 2c selects voltages VA, VB, and VC for adjusting the gradation voltage for each of RGB, which are supplied to selected terminals A to C, for every horizontal line period of an image of the liquid crystal panel 1 (FIG. 18) based on a color selection signal CS, and outputs a voltage V2c. The selection circuits 2d1, . . . , 2dn receive drive voltages V1, . . . , Vq generated by a voltage dividing resistor connected between the voltage V2c and the central voltage Vs1, select drive voltages corresponding to the selection signals S2b1, . . . , S2bn from the drive voltages V1, . . . , Vq, and output a sub-pixel data signal D2.
In the liquid crystal display device, the control circuit 4 outputs the clock signal ck, the control signal Ct, the image signal V4, the color selection signal CS and the central voltage Vs1. Another control circuit (not shown) outputs the color selection signal CS. The clock signal ck, the control signal Ct, the image signal V4 for each of RGB and the central voltage Vs1 are input to the signal electrode drive circuit 2. Then, gradation voltages corresponding to the gradation value of the image signal V4 for each of RGB are selected, and the sub-pixel data signal D2 is generated, which is sent to each of data signal lines X1, . . . , Xn of the liquid crystal panel 1.
In this case, the clock signal ck, the control signal Ct, and the image signal V4 are input to the serial/parallel conversion circuit 2a, from which the gradation values V2a1, . . . , V2an of the image signal V4 for each of RGB are output. The gradation values V2a1, . . . , V2an are input to the decoders 2b1, . . . , 2bn and decoded, from which selection signals S2b1, . . . , S2bn are output. The voltages VA, VB, and VC supplied to selected terminals A, B, and C are selected for every horizontal line period of the image of the liquid crystal panel 1 in the color selection circuit 2c based on the color selection signal CS, and the voltage V2c is output from the color selection circuit 2c. The drive voltages V1, . . . , Vq are input to the selection circuits 2d1, . . . , 2dn, and the drive voltage selected based on the selection signals S2b1, . . . , S2bn is output as the sub-pixel data signal D2 from the selection circuits 2d1, . . . , 2dn. 
In addition, the clock signal ck is input to the scanning electrode drive circuit 3, the scanning signal V3 is generated synchronously with the clock signal ck, and the scanning signal V3 is sent to each of the scanning signal lines Y1, . . . , Ym of the liquid crystal panel 1. In the liquid crystal panel 1, the sub-pixel data signal D2 is supplied to the sub-pixel region selected by the scanning signal V3, and color image corresponding to the sub-pixel data signal D2 is displayed. Herein, voltages VA, VB, and VC are adjusted and input in accordance with the color of the color image on the liquid crystal panel 1, and thus the white balance of the color image is adjusted.
However, in the foregoing conventional general adjustment of the white balance, the use of the gradation value is limited in a particular color. Accordingly, there is a drawback in that combinations of the gradation of RGB, that is, kinds of display colors, are reduced. Moreover, in the method according to the foregoing literature, there is a problem in that the color filter of the liquid crystal panel 1 is limited to the horizontal-stripe type, and it can not deal with the color filters of the vertical stripe type, the mosaic type and the triangle type shown in FIG. 18.
In view of the above, it is an object of the present invention to provide a liquid crystal display device, in which a color correction voltage for each of RGB is generated, a liquid crystal drive voltage (that is, sub-pixel data signal) is independently generated for each of RGB, and a color image is displayed on a liquid crystal panel, and which can deal with various kinds of color filters.
To solve the above-described problems, according to a first aspect of the present invention, there is provided a liquid crystal display device including a liquid crystal panel for displaying a color image, wherein a color correction voltage generation circuit is provided for generating a color correction voltage for each of RGB based on a given input signal for color correction, and the color correction voltage of each of RGB is added to a gradation voltage of an image signal for each of RGB respectively, then the added voltages are supplied to the liquid crystal panel.
According to a second aspect of the present invention, there is provided a liquid crystal display device, including:
a liquid crystal panel having a plurality of data signal lines for receiving a sub-pixel data signal corresponding to a sub-pixel where a pixel is divided into three primary colors of RGB, a plurality of scanning signal lines for receiving a scanning signal, and a plurality of sub-pixel regions provided at points where each of the data signal lines and each of the scanning signal lines intersect, and the liquid crystal panel displaying a color image corresponding to the sub-pixel data signal by supplying the sub-pixel data signal to a sub-pixel region selected by the scanning signal among the plurality of sub-pixel regions;
a gradation voltage generation circuit for generating a plurality of gradation voltages to give gradation to the sub-pixel data signal;
a color correction voltage generation circuit for generating a color correction voltage for each of RGB based on a given input signal for color correction;
a display signal circuit for selecting a gradation voltage corresponding to a gradation value of an image signal for each of RGB from each gradation voltage, adding the color correction voltage for each of RGB respectively to the gradation voltage to generate the sub-pixel data signal, and sending the sub-pixel data signal to each data signal line of the liquid crystal panel;
a scanning signal circuit for sending the scanning signal to each scanning signal line of the liquid crystal panel synchronously with a clock signal; and
a control circuit for outputting the clock signal and the image signal for each of RGB.
According to a third aspect of the present invention, there is provided a liquid crystal display device, including:
a liquid crystal panel having a plurality of data signal lines for receiving a sub-pixel data signal corresponding to a sub-pixel where a pixel is divided into three primary colors of RGB, a plurality of scanning signal lines for receiving a scanning signal, and a plurality of sub-pixel regions provided at points where each of the data signal lines and each of the scanning signal lines intersect, and the liquid crystal panel displaying a color image corresponding to the sub-pixel data signal by supplying the sub-pixel data signal to a sub-pixel region selected by the scanning signal among the plurality of sub-pixel regions;
a gradation voltage generation circuit for generating a plurality of gradation voltages to give gradation to the sub-pixel data signal, inverting a polarity of the gradation voltage in one frame period based on a polarity inversion signal, and outputting the gradation voltage with the inverted polarity;
a color correction voltage generation circuit for generating a color correction voltage for each of RGB based on a given input signal for color correction, inverting a polarity of the color correction voltage in one frame period based on the polarity inversion signal, and outputting the color correction voltage with the inverted polarity;
a display signal circuit for selecting a gradation voltage corresponding to a gradation value of an image signal for each of RGB from each gradation voltage, adding the color correction voltage for each of RGB respectively to the gradation voltage to generate the sub-pixel data signal, and sending the sub-pixel data signal to each data signal line of the liquid crystal panel;
a scanning signal circuit for sending the scanning signal to each scanning signal line of the liquid crystal panel synchronously with a clock signal; and
a control circuit for outputting the clock signal and the image signal for each of RGB.
According to a fourth aspect of the present invention, there is provided a liquid crystal display device, including:
a liquid crystal panel having a plurality of data signal lines for receiving a sub-pixel data signal corresponding to a sub-pixel where a pixel is divided into three primary colors of RGB, a plurality of scanning signal lines for receiving a scanning signal, and a plurality of sub-pixel regions provided at points where each of the data signal lines and each of the scanning signal lines intersect, and the liquid crystal panel displaying a color image corresponding to the sub-pixel data signal by supplying the sub-pixel data signal to a sub-pixel region selected by the scanning signal among the plurality of sub-pixel regions;
a gradation voltage generation circuit for generating a plurality of gradation voltages to give gradation to the sub-pixel data signal, inverting a polarity of the gradation voltage in a specified number of horizontal line periods based on a polarity inversion signal, and outputting the gradation voltage with the inverted polarity;
a color correction voltage generation circuit for generating a color correction voltage for each of RGB based on a given input signal for color correction;
a polarity inversion circuit for inverting a polarity of the color correction voltage for each of RGB in a specified number of horizontal line periods based on the polarity inversion signal, and outputting the color correction voltage with the inverted polarity;
a display signal circuit for selecting a gradation voltage corresponding to a gradation value of an image signal for each of RGB from each gradation voltage, adding the color correction voltage for each of RGB respectively to the gradation voltage to generate the sub-pixel data signal, and sending the sub-pixel data signal to each data signal line of the liquid crystal panel;
a scanning signal circuit for sending the scanning signal to each scanning signal line of the liquid crystal panel synchronously with a clock signal; and
a control circuit for outputting the clock signal, the image signal for each of RGB, and the polarity inversion signal.
According to a fifth aspect of the present invention, there is provided a liquid crystal display device, including:
a liquid crystal panel having a plurality of data signal lines for receiving a sub-pixel data signal corresponding to a sub-pixel where a pixel is divided into three primary colors of RGB, a plurality of scanning signal lines for receiving a scanning signal, and a plurality of sub-pixel regions provided at points where each of the data signal lines and each of the scanning signal lines intersect, and the liquid crystal panel displaying a color image corresponding to the sub-pixel data signal by supplying the sub-pixel data signal to a sub-pixel region selected by the scanning signal among the plurality of sub-pixel regions;
a gradation voltage generation circuit for generating a plurality of gradation voltages to give gradation to the sub-pixel data signal;
a color correction voltage generation circuit for generating a color correction voltage for each of RGB based on a given input signal for color correction;
a display signal circuit for selecting a gradation voltage corresponding to a gradation value of an image signal for each of RGB from each gradation voltage, inverting the color correction voltage for each of RGB at each sub-pixel based on a polarity inversion signal and adding the color correction voltage with the inverted polarity to the gradation voltage to generate the sub-pixel data signal, and sending the sub-pixel data signal to each data signal line of the liquid crystal panel;
a scanning signal circuit for sending the scanning signal to each scanning signal line of the liquid crystal panel synchronously with a clock signal; and
a control circuit for outputting the clock signal, the image signal for each of RGB, and the polarity inversion signal.
According to a sixth aspect of the present invention, there is provided a liquid crystal display device, including:
a liquid crystal panel having a plurality of data signal lines for receiving a sub-pixel data signal corresponding to a sub-pixel where a pixel is divided into three primary colors of RGB, a plurality of scanning signal lines for receiving a scanning signal, and a plurality of sub-pixel regions provided at points where each of the data signal lines and each of the scanning signal lines intersect, and the liquid crystal panel displaying a color image corresponding to the sub-pixel data signal by supplying the sub-pixel data signal to a sub-pixel region selected by the scanning signal among the plurality of sub-pixel regions;
a gradation voltage generation circuit for generating a plurality of gradation voltages to give gradation to the sub-pixel data signal;
a color correction voltage generation circuit for generating a color correction voltage for each of RGB based on a given input signal for color correction;
a multiplexer for selecting and outputting the color correction voltage for each of RGB in accordance with an arrangement of RGB color filters in a horizontal direction of the sub-pixels on the liquid crystal panel, based on a control signal;
a display signal circuit for selecting a gradation voltage corresponding to a gradation value of an image signal for each of RGB from each gradation voltage, adding the color correction voltage for each of RGB output from the multiplexer respectively to the gradation voltage to generate the sub-pixel data signal, and sending the sub-pixel data signal to each data signal line of the liquid crystal panel;
a scanning signal circuit for sending the scanning signal to each scanning signal line of the liquid crystal panel synchronously with a clock signal; and
a control circuit for outputting the clock signal, the image signal for each of RGB, and the control signal.
With the above configurations, the color correction voltage for each of RGB is added to the gradation voltage for each of RGB. Accordingly, the sub-pixel data signal can be controlled and adjusted independently for each of RGB. Therefore, the white balance can be adjusted without reducing the number of the gradation values. Furthermore, the control circuit for outputting the control signal corresponding to the arrangement of RGB of the sub-pixel and the MUX for selecting and outputting the color correction voltage for each of RGB in accordance with the arrangement of RGB of the sub-pixel of the liquid crystal panel are provided, based on the control signal. Accordingly, the present invention can cope with various color filters.